Wireless transmission is more and more popular due to the unlimited applications of the wireless technology. It is widely used in many fields, such as satellite communication, handset communication, or wireless networks. All these facilities apply technique of wireless transmission. However in wireless communication, antenna is an important element, which is used in electromagnetic wave transmission and receiving. Since an antenna is like a liaison among the wireless products. Antennas are supposed to be a key component for its widespread business usage in the future. In order to reduce the cost of manufacture and fit the design criteria, such as small size, light weight, thin or short sizes, how to design and manufacture antenna becomes an important issue.
Chip antennas are a kind of antenna type and are developed recently. This type of antenna packages metal conductor into dielectric material. As far as we know, if electromagnetic wave spreads in the material having higher dielectric constant, then the wave speed will slow down for the sake of material property and the wavelength becomes shorter. The size of antenna will depend on its wavelength. If the wavelength is longer, then the size of antenna will become larger. On the other hand, if the wavelength is shorter, then the size of antenna can be smaller. If the dielectric constant of packaging material is higher, then the whole volume of antenna can be smaller. Almost all products of wireless transformation tend to a trend of compactness, so the invention of chip antenna is very useful for the future development of wireless transformation.
As the prior art techniques is presented in Taiwan Patent No. 480773 The type of antenna starts the stage of three-dimensional structure and apply the technique of low temperature co-combustion (LTTC). However, the manufacturing process of LTTC is very complicated and expensive. In the manufacturing process of LTTC, radiated conductor paths use conductive material plane-printing technology on a ceramic substrate, and then on its adjacent two layers of substrates. Corresponding wire ends form through holes to connect each other. To fill the passing through hole with conductive material to connect the two layers of circuits, this process can build up a three-D structure. Finally, sintering the antenna uses the mean of LTTC (about 800° C.˜900° C.) and composes it into a single unit. Manufacturing process of LTTC limits the choice of conductive circuit and dielectric material. Besides, it also has the problem of sintering contraction and deformation of conductive wires. Because of the disadvantages of LTTC, such as more complex manufacturing process, huger amount of investing cost and lower degree of freedom for antenna designing, those disadvantages leads to increasing the time of preparation for exploiting new products and the increasing cost in research and development. Therefore, LTTC is not qualified to be an efficiency and suitable manufacturing process.
Another example of prior art is presented in Taiwan Patent No. 518801, “chip antenna and method of manufacturing process thereof”. The invention presents a method for packaging partly metal sheet of conductive loop of an antenna by conductive material, then using residue of the loop to follow the surface of the packaged dielectric material for curving. The invention can reduce the measure of area on the substance of antenna. However, the manufacturing process of the antenna is quite complicated and it is difficulty to control the function of antenna.
Besides, another one example of the prior art is presented in the invention of U.S. Pat. No. 6,636,180. The invention presents a type of printing circuit antenna. The kind of micro-strip antenna includes a printed circuit board, metal chips and multiple curved circuits. The metal chips services as grounded surface. On the top and bottom of printed circuit board has conductive circuits and uses through holes to connect therewith so as to form continuous conductive framework, in order to reduce the size of the antenna, but the conductor loop of the antenna is exposed to user's environment. According to the change of user's nearby environment, the residue of the loop central frequency may increase and has different variations.
Above-mentioned prior arts can only produce specific antenna used in particular frequencies. Applying those methods to antenna often has different degree of shifts to the center frequency due to the displacement of the antenna. In the 2.45 GHz of central frequency, the shift can be 200 MHz. If try to calibrate the shift by modifying the antenna loop, that will be complicated and be a huge work. Therefore, the central frequency usually is adjusted by adding capacitor and inductor to the exterior circuits. The solution will increase producing cost and reduce the measure of PC board. Besides, the degree of freedom to apply antenna will reduce.